Traction-motor acceleration and dynamic-braking control



April 18, 1961 G. R. PURIFOY TRACTION-MOTOR ACCELERATION ANDDYNAMIC-BRAKING CONTROL 4 Sheets-Sheet 1 Filed July 2, 1957 uanoamoc mmhmu no no no April 18, 1961 G. R. PURIFOY TRACTION-MOTOR ACCELERATIONAND DYNAMIC-BRAKING CONTROL Filed July 2, 1957 4 Sheets-Sheet 3 w Q 2. P3 8 J3 Sor flfl 3E8? 8 mm mm mm bu 0 1 c n u u u a u u 85 m u 8. h N: it6: m a l rm I mm 6 w E 2E N. E mm mu 5 mm E mm 85 98 N: F 5 5 3 April18, 1961 G. R. PURIFOY 2,989,036

TRACTION-MOTOR ACCELERATION AND DYNAMIC-BRAKING CONTROL Filed July 2,1957 4 Sheets-Sheet 4 T R A H C E C N E U Q E 5 3 5 7R P PMP PT Fig.2.

OPENING OF DOOR RELAY IN NO.I5 POWER-STEP PI5.

United States Patent TRACTION-MOTOR ACCELERATION AND DYNAMIC-BRAKINGCONTROL George R. Purifoy, Pittsburgh, Pa., assignor to WestinghouseElectric Corporation, East Pittsburgh, Pin, a corporation ofPenusyivaru'a Filed July 2, 1957, Ser. No. 669,611

11 Claims. (Cl. 105-61) My invention relates to a control-assembly fortwo diroot-current series motor-means for a common load-device such asan electrically propelled vehicle, and it has particular relation to anelectrical control-system for an electrically propelled railway-car,which is adapted to be operable either singly or as a unit of amultiple-unit train, such as is used in a rapid-transit system.

My invention relates to an improved control-system which eliminates fourrelays on each car, while retaining the smooth acceleration and thesmooth build-up of dynamic brake which is required in this service.

My improved control-assembly also has the advantage of releasing orsubstantially disconnecting the dynamicbraking circuits, when dynamicbrake fades out. The reason for this is, that it is necessary, in allpractical dynamic-braking systems for multiple-unit rapid-transittrains, to-loclc out the dynamic-braking operation, after fade-out of aprevious dynamic-braking operation, until there has been anotherapplication of power, as otherwise a repeated dynamic-brakingoperationwill be too slow in building up its braking-force. In the event of aloss of power on a car, as a result of the blowing of a thirdrail fuse,or from any other cause, it will be necessary to tow the car, usually asa unit of a multiple-unit train, and if the dynamic-braking circuits ofa service braking operation have not been opened, this towing operationresults in a burning out of the resistors in the dynamicbrakingcircuits, because these resistors do not have a sufficient time-ratingto withstand such an operation.

A more detailed explanation of the specific features of my inventionwill be given in the following description, and will be defined in theappended claims, in connection with an illustration of an exemplary formof embodiment of the invention in the accompanying drawing, wherein:

Figs. 1A, 1B and 1C, taken together, constitute a much simplified wiringdiagram of the circuits and apparatus which are necessary for anunderstanding of the novel features of the invention, in a preferredform of embodiment; and

Fig. 2 is a sequence chart of the operation.

Figs. 1A, 1B and 1C represent some of the equipment which is carried bya single electrically propelled railwaycar embodying my invention.Direct-current power is supplied to the car from a third rail 15 or atrolley wire, which is engaged by a third-rail shoe 16, or by a trolleypole, pantograph or other current-collecting equipment carried by thecar. The third-rail shoe 16 is connected, through a third-rail fuse 17,to a conductor 18 which constitutes a supply-circuit for the car.

The traction-motors for the car are direct-current series motors, whichare shown in Fig. 1A, by way of a simple example, as comprising twomotor--armatures A1 and A2, each being associated with its own seriesfield winding SP1 and SP2, respectively. Each of the two series motorsmay be regarded as representing a motor-means or or circuit. Forexample, in most multiple-unit rapidtransit trains, each car or unit isdriven by four motors, connected in two motor-circuits, eachmotor-circuit comprising two motors which are permanently connected inseries with each other.

In Fig. 1A, the first series-motor means or circuit comprises, inseries, an armature-terminal T1, a motor-armature or armatures A1, anarmature-terminal T2, 21 series relay-coil CR of a limit-relay which isalso designated CR, an intermediate circuit or conductor X1, afield-reverser PR1, a field-terminal F2, a series main-field winding orwindings SP1 for supplying the field-excitation for said armature orarmature-s A1, a field-terminal F1, the fieldreverser PR1 again, and anintermediate circuit or terminal X2. The corresponding parts for thesecond series motor means or circuit are indicated at T4, A2, T3, PR2,F4, SP2, F3, PR2 again, and X5, noting that the series relay-coil CR isnot present in this second series-motor means or circuit.

A series-parallel motor-control arrangement is shown in Fig. 1A, inwhich a line-switch LS1 and a ground switch G1 are used aspower-switching means for establishing a power-circuit for energizingthe motors, by connecting the armature-terminal T1 to the supply-circuit18, and connecting the armature-terminal T4 to ground. For completingthe series-circuit connections, a seriesmotor switch IR is closed, inaddition to the powerswitchcs LS1 and G1. For parallel-motor operation,two parallel-motor switches M and G are closed, in addition to thepower-switches LS1 and G1. The parallelmotor switch M provides acircuit-connection between the armature-terminal T1 of one series-motormeans, and the intermediate connection or terminal X5 of the otherseries-motor means; while the other parallel-motor switch G provides acircuit-connection between the armatureterminal T4 and the intermediateconnection or terminal X2. During an intermediate transition-period, atransition-switch J is closed. These motor-controlling connections areall in accordance with a well-known switching-system.

A suitable number of series-connected accelerating resistances are used,as indicated at R10, R11, R12 and R13. The resistance R19 is disposedbetween the supplyline 18 and the first armature-terminal T1, and thisresistance R10 is shorted out by means of a second lineswitch LS2. Theresistance R11 is in series between the intermediate connection orterminal X2 and an intermediate connection-point X3, which is connectedto the terminal T4 through the parallel-connection switch G; and saidresistance R11 is progressively reduced or shorted out by means of anydesired number of switch-contacts or" which only R1 and R7 are shown.The resistance R12 is in series between the intermediate terminal X5 andan intermediate connection-point X4, which is in turn connected to theterminal T1 by the parallel-connection switch M; and said resistance R12is progressively reduced or shorted out by any desired number ofswitch-contacts, of which only R2 and R8 are shown. The resistance R13is in the series-motor connection, which is made between the points X3and X4 by the switch I R, and this resistance R13 is finally shorted outby a transition-switch I, which makes a connection between theintermediate connectionpoints X2 and X5, for obtaining the fullseriespowercircuit connection of the motors.

Dynamic-braking circuits are established by opening the twopower-switches LS1 and G1, and closing a brakingswitch B1 in addition tothe two parallel-connection switchesM and G, also in accordance with awell-known system or arrangement. The braking-switch B1 provides acommon dynamic-braking circuit-connection X6, X7, X8, X9 and X10 betweenthe armature-terminals T3 and T2 of the two series-motor means, thusproviding two 3; dynamic-braking circuits wherein the motor-armature orarmatures of each or" said series-motor means are loaded by the fieldwinding or windings of the other one of said series-motor means, inseries with one of the accelerating reslstances R11 and R12.

During both series and parallel motor operation, and also during dynamicbraking, the switch-contacts R1, R2, R7 and R8 are successively orprogressively closed in any manner which is suitable for progressivelyreducing the resistances. During parallel motor operation, after all ofthe accelerating resistances R11 and R13 have been cut out, thefield-strengths of the motors are progressively reduced, to provideshunted-field operating-conditions.

fields are reduced by equipping each of the series field windings SP1and SP2 with a field-shunt, comprising an inductive reactor SX1 and X2,as the case may be, and a variable resistor SR1 or SR2, respectively.The fieldshunts SXl-SRE and SX2SR2 are first connected in parallelrelation to their respective field-windin s SP1 and SP2, by means ofcontact-terminals C11 and C10, respectively, of any suitableprogressively or sequentially operating field-controlling means, whichis herein illustrated as an electrically operated drum-typefield-controller PC. After the respective field-shunts have beenconnected into operation, the field-shunt resistances SR1 and SR2 arethen progressively shorted out by successive controllerpoints, of whichonly C13 and C17 are shown for SR1, and only C12 and C16 are shown forSR2, as the fieldcontroller PC is moved from its initial full-fieldposition PP, through its intermediate positions, of which only P1 and P3are shown, to its shunted-field position SP, at which point thefield-winding currents are reduced to about 40% of their unshuntedvalues.

During dynamic braking, the braking-switch B1 connects the two motorsthrough the common dynamic-braking circuit-connection X6 to X10, whichcontains a fivepart braking-resistance R14 which is not a part of themotor-accelerating circuit. This braking-resistance R14 is used, inaddition to the previously mentioned accelerating-resistances R11 andR12, in establishing the complete dynamic-braking circuits. Thebraking-resistance R1 is progressively reduced in value, by means of asuitable operation of brakingswitches B2 to B5, in addition to the mainbraking-switch B1, during the dynamicbraking operation, and after thebraking-resistance R14 has been reduced in value as much as it is goingto be reduced, by the braking-switches B1 to B5, theacceleration-resistances R11 and R12, or portions thereof, areprogressively shorted out, or reduced in value, by theaccelerationswitches R1, R2, R7 and R8.

The progressive operation of the various resistanceshorting switches,during both motoring operation and dynamic braking, is under theautomatic controlof a suitable limit-relay CR, which is energized to becontrollably responsive to conditions which accompany current-incrementsin the motor. Such a limit-relay is illustrated, in Figs. 1A, 1B and 1C,in the form of a single current-relay CR which is provided, inaccordance with my present invention, with at least four operatingcoils,namely the previously mentioned series coil CR, a kick-coil KC, a

spot-coil SC, and a rate-coil RC, all acting cumulatively to cause a reay-response. The series soil CR is a oneturn current-coil which isserially connected between the points T2 and X1 in themotor-accelerating part of one of the motor-circuits, as is well-known.The kick-coil KC is a multiturn shunt relay-coil which is connectedacross the terminals T3 and X5 of the series main-field winding SP2 ofthe other motor-circuit. with a variable resistor R15 connected inseries with the kick-coil KC for recalibrating purposes, as will besubsequently described. The spot-coil SC is a multiturn braking-currentcoil which is energized across a portion 22-T2 of the braking-resistanceR14, as will be subsequently described. The rate-coil RC is a multiturnbattery-energized coil which is conlln accordance with a usualarrangement, the motorl I 77i a trolled for recalibration purposesduring motoring and braking, as will be subsequently described.

As shown in Fig. 1B, this limit-relay CR has a backcontact 66, which isnormally closed, in the non-actuated or low-current position of therelay, and it also has a make-contact 67, which is closed when therelay-excitation is considerably higher than that which is necessary toopen the back-contact 66.

All of the'electrically controlled relays and switches which are shownin the drawing are diagrammatically indicated as having verticalswitch-stems (indicated by dotted lines), which are biased by gravitytoward their lower most positions, and all of these relays and switchesare shown in their deenergized or non-actuated positions. All of therelays and switches are electrically controlled, and they areillustrated as being electrically or magnetically operated, by means ofan appropriately numbered or lettered coil or solenoid, represented by acircle, acting magnetically to lift an armature which is representeddiagrammatically by a smaller circle inside of the coil-circle. Ingeneral, the same switch-designation is applied to any particularswitch, its coil, and its contacts, by way of identification of theparts belonging to a given switch or relay.

Energy for the various relay-circuits or control-circuits is provided bymeans of a battery B on each car, as shown at the top left corner inFig. 1A. The negative terminal of the battery is permanently grounded,to constitute the negative bus of the relay-circuits; while the positiveterminal of the battery is connected, through a battery-switch BS, tothe positive bus of the relay circuits.

The exemplary field-controller FC,-Which is illustrated in the top leftportion of Fig. 1A, consists of a drum C20, carrying sixcontact-segments C21 to C26. The segment C21 engages the field-terminalF2 and the odd-numbered controller-contacts C11 to C17 in the previouslydescribed field-shunting progression, while the segment C22 engages thefield-terminal P4 and the even-numbered con troller contacts C10 to C16,in the previously described field-shunting progression. The segment C23engages two controller-circuits C2 and C2 in the full-field position PPof the field-controller PC. The segment C24 engages twocontroller-circuits C3 and C4 in the controllerpositions PP through P3.The segment C25 engages two tontroller-circuits C1 and C2 in thefull-field position P1 through SP; and these controller-circuits C5 andC6 are connected to adjustable intermediate tap-points C5 and C6 on thekick-coil resistor R15. The segment C26 engages two controller-circuitsC7 and C8 in the controller-positions PF through P3, maintaining thisconnection to a point a little further beyond the position F3 than thesegment C24.

The drum C20 of the field-controller PC is operable to its full-fieldposition PP by any suitable means, which is simply illustrated in theform of a solenoid or magnet-coil PC-FP, which is energized betweenground and a controller-circuit C9. The drum C20 is operable to itsshuntfield position SF by any suitable means which is illustrated as asolenoid or magnet-coil PC-SP, which is energized between ground and thecontroller-circuit C7. The drum C20 remains in its set position, ifneither of its coils FG-PP or PC-SP is energized, or if both of saidcoils should be energized simultaneously.

At the top of the main motor-circuits in Fig. 1A, I show thesupply-circuit 18 as being used to energize a linerelay LR through aback-contact 19 of the second lineswitch LS2. This line-relay LR picksup when an adequate.line-voltage appears on the supply-conductor 18.This line-relay has a make-contact 20 which bypasses the LS2back-contact 19 when the line-relay is energized.

The braking-current-responsive circuit 22T2-, which is shown immediatelybelow the main motor-circuits in Fig. 1A, is energized from a tap-point22 in the last section of the braking-resistance R14, so that thiscircuit 22-T2 is not energized except when a braking circuit isestablished.

Thus, in accordance with my present invention, I provide abraking-current-responsive circuit extending from the conductor 22through a make-contact 23 of the braking-circuit contactor B5, andthence through a circuit 24 to a hold-coil M-Hold of theparallel-connection switch M, then to a circuit 25, and finally througha back contact 26 of the ground-switch G1, to the conductor T2.Connected between the circuit-points 24 and 25, there is also ahold-coil G-Hold of the parallel-connection switch G. These twohold-coils M-Hold and G-Hold are intended to be symbolic of any meanswhich will hold their respective switches or contactors closed afterthey are once closed by other means (to be subsequently described), butwhich will not close or energize these switches from a deenergizedposition.

Also in accordance with my present invention, anotherbraking-current-responsive circuit is shown as extending from theconductor 22, through a back-contact 27 of a brake-actuator BA whichwill be subsequently described, and thence through the spot-coil SC ofthe limit-relay CR, to the circuit T2. This is for the purpose ofenergizing the spot-coil SC only during the spotting operation.

A final braking-currcut-responsive circuit is also shown, extending fromthe conductor 22, through the magnet-coil LOM of a subsequentlydescribed lock-out magnet, and thence through a back-contact 28 of theresistance-shorting switch R8, to the circuit T2.

The kick-coil resistance R is provided with a terminal 29 at the end ofthe resistance which is closest to the tap-point C6, and this terminal29 is shown as being connected, through a back-contact 30 of the secondlineswitch LS2, to the aforesaid tap-point C6.

The various electrical control-circuits for a train are under thecontrol of a number of trainline wires, which extend from car to car,throughout the entire length of the train (not shown). As shown at thebottom of Fig. 1A, each car is provided with two couplers 31 and 32, onecoupler at each end, these couplers being used for making drawbarconnections with other cars of a train, and also being used for makingvarious trainline Wireconnections, such as connections for certaintrainline wires, 21, 1, 2, 4, 6, 7, and GS, to use their customarydesignations, and also being used for making various air-connections,such as connections for a so-called straightair pipe SA which isprovided on each car. Connected in series with the trainline wire 21, ineach car, are one or more door-interlocks DI, which are closed by theclosure of the respective doors on the car. The respective couplers 31and 32 are provided with coupler-switches CS1 and CS2, respectively,which are closed when the corresponding coupler is uncoupled, and whichare opened when the corresponding coupler is coupled to a coupler ofanother car. These coupler-switches CS1 and CS2 are used to connect thetrainline wire 21 to either one of two conductors 33 or 34,corresponding to the couplers 31 and 32, respectively.

Each end of each car is provided with a motormans master controller MC,only one of which is indicated in the drawing, namely the controllerwhich is connected to the wire 33. Since the only master controllerwhich is used, either in a single car or in a multiple-unit trainconsisting of a plurality of cars of the type herein illustrated, is thecontroller at the front end of the car or train, the master controllerMC which I have illustrated is assumed to be at the front end of thecar, if the car is being operated by itself, or at the front end of thetrain, if the car is be ing operated at the front end of a multiple-unittrain. The master controller at the other end of the car is notillustrated, in Fig. 1A, as it is a duplicate of the master controllerMC at the front end, with the understanding that the master controllerat the rear end will remain in its off position.

Each master controller MC consists of a reverser drum RD and a main drumMD.

The main drum MD is provided with two contact-segments MDl and MD2, andthis drum is provided with an off-position and three on-positionsnumbered 1, 2 and 3.

The reverser drum RD has an off-position, centered between forward andreverse positions. In its elf-position, the reverser drum RD connectsthe wire 33 or 34, as the case may be, to the. positive bus In eitherits forward or reverse position, this reverser drum RD connects the wire33 or 34, as the case may be, to a wire 35, which extends through theoperating coil DR of a door-relay DR, and thence extends on, to thenegative bus The re sult of this arrangement is that the mastercontroller at the rear end of the train will have its reverser drum RDin the off position, and the corresponding coupler-switch CS2 will beclosed, so that that end of the trainline wire 21 will be connected tothe positive bus of the rear car. If all of the door-interlocks D1 areclosed, throughout the length of the train, this positive energizationof the trainiine wire 21 will extend on, to the front end, where thecoupler-switch CS1 will again be closed, and the doorrelay DR will beenergized at 35, subject to a closed position of all of the doors of thetrain.

The door-relay DR has a make-contact 36, which is connected between thetrainline wire 6 and a conductor 14, which will be subsequentlydescribed. This door-relay contact 36 is also bypassed by a push buttonPB which is within convenient reach of the rnotorman, from his stationin front of the master controller MC, so that, in an emergency, if oneof the doors of the train is open, and

cannot be closed, the motormancan obtain control-powe=n by depressingthe push button PB, thus completing a circuit between the conductors 6and 14. As soon as the push button PB is closed, and as soon thereafteras the main drum MD of the master controller is moved from itscit-position to any on-position, the trainline wire 6 will be energized,and hence the conductor 14 will be energized. A push-button hold-coilPB-Hold is energized, between the conduetor 14 and the negative bus soas to hold the push button closed until the conductors 6 and 14 areagain deenergized by a return of tr e main drum MD to its off-position,which deenergizes the trainline wire 6, as will be subsequentlydescribed.

In either its forward or reverse position, the reverser drum connectsthe positive bus to a wire A+, which leads to one of thecontacbterrn-inals of the main-drum segment MD The reverser drum RD alsoreceives energy from an auxiliary positive bus B-lwhich extends from acontactterminal of the main-drum segment MD2. in tie forward position ofthe reverser drum, this auxiliary positive bus 3+ is connected to thetrainline wire 1; and in the reverse position of the reverser drum, thisauxiliary positive conductor 3+ is connected to the trainline wire 2.

The main-drum contact-segment MD has three terminals, in addition to theterminal of the aforesaid positive wire A+. In the first, second andthird on-positions of the main drum MD, this contact-segment MDllenergizes the trainline wire 6; in the second and third positions of themain drum MD, the segment MDI energizes the trainline Wire 4; and in thethird position of the main drum MD, the segment MDl energizes thetrainline wire 7.

In the off-position of the main drum MD, no circuiteontacts orconnections are made; but in the first, second and third oil-positionsof this drum, the second segment MDZ connects the wire 14 to theauxiliary positive conductor 8+ and also to the trainline wire GS. It isto be noted, however, that, during the oil-movement of the main drurnM), the segment MD! energizes the trainline wire 6 from the auxiliarypositive conductor A+, and the segment M132 energizes the auxiliarypositive conductor B+ from the wire 14, both of these connections beingmade slightly before the segment MDZ energizes the trainline wire GS.Contrariwise, during the off-movement. of the aseopse main drum, inpassing from the No. 1 on-position to the ofi-position, the trainlinewire GS is deenergized prior to the deenergization of the trainline wire6, and also prior to the deenergization of the trainline wire 1 or 2, asthe case may be.

Electrically propelled rapid-transit cars and multipleunit trains areprovided with air-brake equipments for stopping the car or train,unaided by dynamic braking, in an emergency, but normally operative onlyupon fade-out of the dynamic-braking force, when the dynamic braking hasbrought the car or the train nearly to a standstill, for then bringingthe car or train to a complete stop. As shown at the bottom of Fig. 1A,a brake-valve BV is provided, for supplying compressed air at acontrollably varied pressure to the straightair pipeline SA when aservice braking-operation is required, that is, when a substantialbraking-force is to be applied to the car or train, as distinguishedfrom the very small, usually negligible, braking-forces which arenormally produced by the dynamic-braking circuits during the so-calledspotting" operation of the dynamic braking equipment, which will besubsequently described.

The pressure of the air in the straight-air pipe SA is responded to by abrake-actuator cylinder BA, which is connected to said straight-airpipe, and which is provided with a piston 37 which lifts a verticallyillustrated dottedline actuator-stem, also designated BA. Heretofore,this brake-actuator BA has been used to adjust the position of abrake-actuator rheostat, which is shown at BKG in the middle of Fig. 1C,so as to adjust the position of this rhcostat in accordance with theseverity of the braking operation which is called for by the position ofthe brakevalve BV, as will be subsequently described. In accordance withmy present invention, I provide the brake-actuator BA with threeelectrical contacts 27 (Fig. 1A), 69 (Fig. 1B), and 140 (Fig. 1C), allof which are actuated as soon as the brake-actuator begins to move, inresponse to any on-position of the brake-valve EV. This use of suitableelectrical switches or interlocks on the brakeactuator BA, according tomy present invention, makes it possible for me to omit one of the relayswhich has previously been required in rapid-transit cars of this type,as will be subsequently explained in connection with the operation of myinvention.

As has been common in previous dynamic-braking railway-cars, thestraight-air pipe SA is connected to airbrake equipment of each car bymeans of a lock-out valve LOV, which is electrically closed, upon theenergization.

of the lock-out magnet LOM, and which is released when the look-outmagnet LOM becomes substantially deenergized. In this way, when theso-called fade-out point has been reached, and the braking-force of thedynamic-braking circuits becomes very small, the air-brake equipment isbrought into operation, to finish bringing the train to a completestandstill.

At the .top of Fig. IE, it will be noted that I have illustrated asimplified or schematic version or representation of a reverser-relayRR, which is shown as being provided with a forward-switch FOR, and areverse-switch REV, which are mechanically joined by a lever 38, whichcauses one switch to be up while the other is down. These forward andreverse switches may be regarded as carrying main-circuit contacts whichconstitute the diagrammatically indicated field-reversers PR1 and PR2which are shown in the main-circuit diagram in Fig. 1A.

In Fig. 1B, I have shown the reverser-relay RR in the position which itoccupies for producing a forward movement of the car or train. I haveshown control-circuits including a connection from the trainline wire 2through a closed interlocking contact 39 on the forward-switch FOR, tothe reverse-swtich operatingcoil REV, and thence on, to a circuit orconductor it). I have also shown a connection from the trainline wire 1through the forward-switch operating-coil FOR to an open interlockingcontact 42 on the reverse-switch REV, and thence on,

to the conductor 40. This conductor 40 is then connected to the negativebus through a back-contact 41 of the line-switch LS1. It will be notedthat, before the reverseswitch RR was moved to its illustratedforward-position, the reverse-switch contact 42 was closed, so that,when the trainline wire 1 was first energized, the forward-switch coilFOR was momentarily energized, long enough to properly adjust theposition of the reverse-relay RR, before the energizing circuit wasopened by the opening of the reverse-switch contact 42.

The first on-position of the master controller MC, in Fig. 1A, is atrain-switching position, in which the car or train is slowly moved, atits minimum speed, for moving the car or train for short distances. Inthis No. 1 controller-position, either the control-wire 1 or 2 isenergized, depending upon the desired direction of trainmovement, andthe control-wires GS and 6 are also energized.

As shown in Fig. 1B, a circuit is provided from the control-wire 1,through a closed interlock 43 on the forward-switch FOR, to a conductor44, and another circuit is provided between the non-deenergizedcontrol-wire 2, and a now-open interlock 45 on the reverse-switch REV,to the aforesaid conductor 44. This conductor 44 energizes anexciting-circuit which first extends through the operating coil LS1 ofthe line-switch LS1, then extends through a back-contact 46 of thebrake-switch B1, a make-contact 47 of the line-relay LR, a back-contact48 of the brake-switch B4, a circuit 49, a back-contact 5t) 01'' theparallel-connection switch M, and a back-contact 51 of theparallel-connection switch G, to the negative bus A hold-circuit is alsoprovided, between the circuit 49 and the negative bus through a makecontact 52 of the line-switch LS1.

In accordance with my present invention, the next circuit which is shownin Fig. 1B is a circuit-connection 53 from the positive bus through aback-contact 54 of the ground-switch G1, to a power-offswitching-circuit 55.

In accordance with a joint invention of Norman H. Willby and myself, asset forth in our application Serial No. 669,550, filed July 2, 1957, abackwardly extending circuit is next provided, from the power-offrelayingcircuit 55 to the controller-terminal C3 of thefield-controller, for the purpose of causing the contact-segment C24 ofthe field-controller FC, in Fig. 1A, to be in series with a hold-lineC4, in the field-controller positions FF through F3.

In the order in which the circuits are shown in Fig. 1B, the nextcircuit is a connection from the trainline wire 4, through amake-contact 56 of the line-switch LS1, to a control-circuit 57 whichwill be subsequently referred to. It will be recalled that the trainlinewire 4 was first energized in the No. 2 on-position of the main drum ofthe master controller MC. This is the mastercotnroller position in whichit is desired to initiate the progressive operation of theresistance-reducing switches in the series motor-connection of thetraction motors A1 and A2, in order to smoothly accelerate the car ortrain.

It will be noted, from Fig. 1B, that I have provided a secondenergizing-circuit, for the control-circuit 57, which extends back fromthe power-oil? switching-circuit 55, and which includes a back-contact58 of the ground-switch G1. This energizing-branch of thecontrol-circuit 57 is used during the dynamic-braking operation, as willbe subsequently explained.

The next circuit shown in Fig. 1B is an energizingcircuit from thetrainline wire GS to the operating coil G1 of the ground-switch G1, andthence to the negative bus Next comes a circuit from the trainline wire6, through a make-contact 59 of the line-switch LS1, to a conductor 60,and thence on, through a make-contact 61 of the ground-switch G1, to apower-on switching-circuit 62.

9 From this power-on switching-circuit 62, a connection ex tends back,or to the left, through a baclocontact 63 of the parallel-connectionswitch G, and a hack-contact 64 of the transition-switch J, to aconductor 65, which energizes the operating-coil IR of the series-motorswitch JR.

Referring back again to the control-circuit 57, it will be noted thatthis circuit extends down to a point where it is connected to the twocontacts 66 and 67 of the limitrelay CR. The contact 67 is a limit-relaymake-contact, which completes a circuit from the conductor 57 to aconductor 68. In accordance with my present invention, the circuit fromthis conductor 68 extends through a backcontact 69 of the brake-actuatorBA, and a back-contact 70' of the second line-switch LS2, to thecontroller-circuit C8, which is connected, by the field-controllersegment C26 in Fig. 1A, to the controller circuit C7, in all positionsof the field-controller FC except the full-shuntedfield position SF. Itwill be recalled that the controller circuit C7 energizes thefield-controller magnet-coil FC-SF, which moves the field-controllerdrum C20 toward the shunted-field position SF.

The limit-relay contact 66 is a back-contact, which completes a circuitfrom the conductor 57 to a conductor 71, referred to below.

Referring now to the conductor 61 in Fig. IE, it will be noted that thisconductor has a branch extending downwardly to a backwardly orleft-extending circuit, through a make-contact 72 of the series-motoringswitch I R, to a circuit 73, which extends on, still further backwardly,or to the left, to connect with the controller wire C9 which energizesthe full-field magnet-coil FC-FF (Fig. 1A), for moving thefield-controller drum C20 to its full-field position FF.

Next, in Fig. 1B, the conductor '71 is shown as having a backwardly orleftwardly extending connection 71, which passes through a back-contact7 4 of the line-switch LS1, to the aforesaid circuit 73 which isconnected to the full-field controller-conductor C9. This circuit 73also has a downwardly extending branch 73, for purposes which will beexplained in connection with Fig. 1C.

Next, in Fig. 1B, another leftwardly extending branch of the circuit 71is shown as passing through a makecontact 75 of the brake-switch B to aprogress-wire 76, which is used, during dynamic braking, in theprogressive control of the resistance-shorting switches R1 to R8.

Fig. 13 next shows a second energizing-circuit for the progress-wire 76.This second circuit extends back (or leftwardly) from the conductor 71to a make-contact 77 of the ground-switch G1, and thence to a conductor78, which extends on leftwardly, until it connects to the progress-wire76. This progress-wire 76 is used, during the acceleration of thetraction motors, in the progressive control of the second line-switchLS2, the resistanceshorting switches R1 to R8, and the transition-switchI.

The conductor 78, in Fig. 1B, has a downwardly extending connection,which extends to the left, through a make-contact 79 of theseries-motoring switch JR, and

then through a back-contact 86 of the second line-switch LS2, to anenergizing-circuit 81 which energizes the operating-coil LS2 of saidsecond line-switch LS2. A hold-circuit is also provided, for energizingthe conductor 81. of the line-switch LS2, through an LS2 makeoontact 82,which receives its energization from the previously mentioned conductor61?. I

Just below the middle of Fig. 113, there is shown a circuit extendingfrom the progress-wire 76 through a make-contact 83 of the LS2 switch,to a conductor 84, and thence through a back-contact S5 of the firstresistance-switch R1 to a conductor 86, and thence through theoperating-coil R1 of this switch to a conductor 87, and finally througha make-contact 83 of the series-motoring switch JR to a conductor 89,which will be subsequently referred to. The LS2 contact 83, at thebeginning of this circuit, closes, with the closing of the secondline-switch LS2, at the beginning of the motor-accelerating progression.This contact 83 is bypassed by a makecontact 99 of the braking-switchB1, so as to reenergize the progression-circuit 8-4 to the firstresistance-switch R1, at the proper time during the dynamic-brakingprogression, as will be subsequently pointed out.

Next, in Fig. 113, there is shown a circuit 91 from the positive busthrough a make-contact 92 of the line-switch LS1 to a conductor 93, thenthrough a makecontact 94 of the line-switch LS2 to a hold-wire 95, andfinally through. a make-contact 96 of the first resistanceswitch R1 tothe energizing-circuit 86 of this switch.

As shown in Fig. 1B, the progression continues, from the progress-wire76, through a make-contact 97 of the resistance-switch R1 and aback-contact 98 of the resistance-switch R2, to a conductor 99, andthence through the operating-coil of the resistance-switch R2 to thepreviously mentioned conductor 37, and then through a make-contact 1th?of the parallel-connection switch G to the previously mentioned circuit89. Next is shown a circuit from the hold-wire C4 through a back-contact101 of the line-switch LS1 to the previously mentioned hold-wire 95, andthen through. a make-contact 102 of the resistance-switch R2 to theenergizing-circuit 99 of this switch.

A progress-connection is next made from the progressline 76, through anR2 make-contact 103, an R7 backcontact 104, a circuit 105, and the R7energizing-coil, to the circuit 37. in accordance with my presentinvention, a hold-circuit is provided from the control-circuit 57through an R7 make-contact 106 to the energizing-circuit 1115 of this R7switch.

A progress-circuit is next shown, from the progresswire 76, through anR7 make-contact 107, an R8 backcontact 108, a circuit 169, and the R8energizing-coil, to the circuit 87. In accordance with my presentinvention, a hold-circuit is provided from the control-circuit 57through an R8 make-contact 11d to the circuit 109.

In accordance with my invention, a circuit also extends to the left,from the bottom of the control-circuit 57 in Fig. IE, to an LS1hackcontact 111, and thence to a conductor 112 which will be furthermentioned in the description of Fig. 1C.

The bottom of the conductor 87 in Fig. 113 has a leftwardly extendingextension, which leads through a makecontact 113 of the brakeswitch B4to the previously mentioned circuit 59, which is continued on, in Fig.1C.

At the top of Fig. 1C, the circuit 89 is shown as continuing on, to thenegative bus through a backcontact 114 of the transition-switch I.

From the progress-line 76 in Fig. 1C, a circuit next extends through anR8 make-contact 115 to a conductor 116, in accordance with my presentinvention. A second energizing-circuit for this conductor 116 is alsoprovided, extending to the left from the power-on switching-circuit 62through a make-contact 117 of the transition-switch J, to said conductor116. A circuit from said conductor 116 then extends on, to the left,through a back-contact 118 of the parallel-connection switch M, andthrough a back-contact 119 of the braking-switch B1, to a conductor 120which energizes the operating-coil J of the transition-switch I.

A branch-circuit is next shown, in Fig. 1C, extending from the conductor112 of Fig. 1B, and passing through an R7 back-contact 121 to a circuit122, this branch-circuit being effective during the dynamic-brakingoperations.

A circuit is next shown, in Fig. 1C, extending from the trainline wire'7, which is energized, in the third on-position of the mastercontroller MC in Fig. 1A, for the purpose of initiating the parallelmotor-connection in the accelerat ing control or power-operation of thetraction motors A1 and A2 of Fig. 1A. This branch-circuit extends fromthe wire 7 through a baclccontact 123 of the last acceleratingresistanceswitch R8, and a make-contact 124 of the transition-switch I, to thepreviously'mentioned conductor 122. The circuit 122 extends on, througha JR back-contact 125 to a conductor 126, and thence through amakecontact 127 of the parallel-connection switch G to a circuit 128.Another connection is made from the conductor 126, through aback-contact 129 of the resistance-switch R1, to said conductor 12%.This conductor 128 constitutes an energizing-circuit for energizing boththe G-coil and the M-coil of the two parallel-operation switches G andM. A hold-circuit is also provided, extending to the left from thebottom of the power-on switchingcircuit 62, and thence through amake-contact 129 of the M-switch, to the previously mentioned conductor126.

It will be observed that, before the parallel-connection switches M andG were closed, during the power-operation of the motors, thetransition-switch J had to be closed, as will be seen from its interlock124; and it will be further observed that, when this transition-switch Iclosed, it opened up the series-motoring switch I R, at the J -interlock64 in Fig. 1B, and it opened up all of the resistanceswitches R1 to R8,at the J-interlock 114 in Fig. 1C. The progressive operation of theresistance-switches R1 to R8 then commenced all over again, from theprogress-wire 76 in Fig. 1B, the negative circuits of the coils R1 to R8being completed through the G-interlock 100, in Fig. IE.

it will be observed, however, that when the parallelconnection switchesM and G are closed during the braking-operation of the motors (throughthe R7 interlock 121 in Fig. 1C), the above-described progression of theresistance-switches R1 to R8 will not commence immediately, because thefirst progression will be established through the control of thebrake-switches B1 to B5, as will be subsequently described.

The next control-circuit in Fig. 1C extends from the bottom of theprogress-line 76, and continues through a make-contact 136 of theparallel-connection switch M and a make-contact 131 of the lastresistance-switch R8, to the field-controller circuit C7 which energizesthe shuntfield coil FCfiSF of the field-controller FC in Fig. 1A. Duringthe motoring operation, this energization of the shunt-field coil FC-SFoccurs at the end of the full-field parallel-connection acceleration,and it initiates the progression of the field-controller PC from itsfull-field position FF to its shunt-held position SF. However, duringthe dynamic-braking operation, this energization of the shunt-fieldcontroller-coil FC-SF occurs at fade-out, and it produces nocontroller-movement, because the full-field controller-coil FC-FF isbeing simultaneously energized, through the C9 circuit which extendsfrom the conductor 73 in Fig. 1B.

In Fig. 1C, a branch-circuit 93 extends down, from the conductor 93 inFig. l and is used to energize an energizit1g-circuit 132 of therate-coil RC of the limit-relay CR, through a weight-controlled rheostatWT, and an adjustable resistance R16. This rate-coil energizing-circuit,which includes the weight-responsive rheostat WT, is energized when thecircuit 93 is energized, and it will be seen, from Fig. 113, that thiscircuit R3 is energized from the positive wire- 91 as soon as thepower-operation of the motors is initiated, as supervised by the LS1interlock 92. The weight-responsive rheostat WT is a known device, whichis automatically adjusted according to the variable weight or live loadcarried by the car, so that the rate-coil RC is the more stronglyexcited during lightweight conditions, during the acceleratingprogression of the motors, thus controllably reducing the minimumcurrentsetting at which the limit-relay CR picks up and opens its back-contact66 (Fig. 1B) during the poweroperation of the motors. This is awell-known, and practically necessary, expedient, the operatingmechanism thereof being symbolically indicated by the letters WT.

in Fig. 1C, a second energizing-circuit is provided for the conductor132 of the rate-coil RC. This second energizing-circuit extends back, tothe left, from the power-off switching-circuit 55, which is energizedonly when the power-operation of the traction-motors A1 and A2 of Fig.1A is deenergized, as indicated by the G1 interlock 54 in Fig. 1B. InFig. 1C, therefore, a circuit is provided, which extends to the left,from the power-off switchingcireuit 55, through a back-contact 133 ofthe groundswitch G1, to a braking-responsive rheostat EKG, and thencethrough an adjustable resistance R17 to the energizing-circuit 132 ofthe rate-coil RC. The resistanceadjusting contact-arm of thebraking-responsive rheostat EKG is moved by the brake-actuator BA, in anamount which is dependent upon the amount of braking which is called forby the'brake-valve BV (Fig. 1A), which controls the air-pressure in thestraight-air pipe SA, to which the brake-actuator cylinder BA isconnected, as shown in Fig. 1A. This braking-responsive rheostat BKG hasits resistance automatically increased in response to the amount ofbrake-application called for by the brake-valve BV, so that therate-coil RC has its maximum dynamicbraking excitation when a lowbraking-rate is called for, thus providing a low minimum-current settingat which the limit-relay CR picks up and opens its back-contact 66 (Fig.1B) during dynamic braking.

The next control-circuit'in Fig. 1C shows how the brake-switch B1 isenergized, in order to initiate dynamic braking. Thus, near the bottomof the power-off switching-circuit 55, a leftwardly extendingbranch-circuit extends through an R2 back-contact 134 and a B4backcontact 135 to a circuit 136, which is extended through theoperating-coil B1 of the brake-switch B1 to a circuit 137, the negativeconnection of which is completed through a subsequently describedback-contact 152 of the brake-switch B4. It will be observed that thisbrakingcircuit is not normally established until the main drum MD of themaster controller MC is moved to its cit-position in Fig. 1A. Thisoft-movement of the master controller first causes the opening of theground-switch G1, and later the opening of the line-switches LS1 andLS2. The opening of the G1 switch opens the interlock 61 in Fig. 1B,thereby deenergizing the holding-circuit 62 129 (Fig. 1C) of the twoparallel connection-switches M and G, and also deenergizing theholding-circuit 62-117 (Fig. 1C) of the transition-switch I, and alsodeenergizing the energizing-circuit 6263-64 (Fig. 1B) of theseries-connection switch IR. Thus, whichever of these switches M, G, l Ror I had been closed are opened, thus opening all of theresistance-switches R1 to R8, at either the JR interlock 88 (Pi 13), orthe G interlock 100 (Fig. 1B). The opening of the resistance-switch R2energizes the B1 switch, through the R2 interlock 134 (Fig. 1C).Meanwhile, the line-switch LS1 is open, and when it opens, it energizesthe parallel-connection swi)tches M and G, through the LS1 interlock 111(Fig. 1B

These operations result in the closure of the switches M, G and B1, thusestablishing the dynamic-braking circuits, with all of thebraking-resistance R14, and all of the accelerating resistances R11 andR12 in circuit,

thus producing a very small braking-current, and a very smallbraking-force, which is normally negligibly small and which makes itfeasible to establish a very weak dynamic-braking circuit in readinessfor a service application of dynamic brake, as will be subsequently described. This weak operation of dynamic brake is called spotting. Duringthe spotting-operation, the spot-coil SC (Fig. 1A) of the limit-relay CRis energized, from the tapped portion 22T2 of the dynamic-brakingresistance R14, and the field-controller is caused to pr0 gress, in onedirection or the other, under the control of the make and break contacts67 and 66 (Fig. 1B) of the limit-relay CR, in order to spot theoperating-conditions of the dynamic-braking circuit in accordance withthe speed of the car, so that, if and when a service braking-operationis called for, the service dynamicass ose" 13 braking conditions may beentered into smoothly and without overshoot.

Returning, again, to Fig. 10, it will be noted that the bottom of thepower-off switching-circuit 55 has a leftwardly extending branch-circuitwhich extends through a B make-contact 138 and a B1 make-contact 139, tothe energizing-circuit 136 of the B1 relay, thus establishing ahold-circuit therefor.

Next, in Fig. 1C, there is shown a circuit from the wire "/3 of Fig. 1B,extending through a make-contact 1411 of the brake-actuator BA, toenergize the field-controller circuit C2, and hence the progress-wire C1when the field-controller segment C23 is energized in the fullfieldposition FF of the field-controller FC in Fig. 1A.

As has been previously stated, the three brake-actuator contacts 27, 69and 140 are a novel feature of my invention, whereby a servicedynamic-braking operation is initiated by the initial response of thebrake-actuator cylinder BA at the bottom of Fig. 1A, in response to themovement of the brake-valve BV to any on-position. Thus, I avoid thenecessity for using a separate electrically operated braking-relay,which was first shown in my Patent 2,318,330, of May 4, 1943, and whichhas been standard equipment in the dynamic-braking control ofmultiple-unit trans and rapid-transit cars. My brake-actuator interlock27 in Fig. 1A disconnects the spot-coil SC of the limit-relay CR, thusincreasing the current-setting of the limit-relay CR. Thereafter, eachtime the braking-current subsides to a value which is low enough toclose the limit-relay back-contact 66 in Fig. 1B, a step in theservice-braking progression is made, through the circuit 71-7473. Thisbraking-progression circuit is connected to the full-fieldcontrollercircuit C9, which notches the field-controller FC (Fig. 1A)toward its full-field position FF, and when the full-field position FFis reached, the controller-contact C243 energizes the progress-wire C1from the controllercircuit C2, which is in turn energized, by thebrakeactuator contact 141) (Fig. 1C), from this same brakingprogressioncircuit 717473 (Fig. 1B).

The next control-circuit which is shown in Fig. 1C is a brancl1-circuitwhich extends from the progress-wire C1 through a B1 back-contact 141and a B3 make-com tact 142 to the energizing-circuit 136 of the B1switch.

Next, in Fig. 1C, there is shown a branch-circuit from the progress-wireC1, through a B5 make-contact 143 to a conductor 144. A secondenergizing-circuit for this conductor 144 is shown as extending from theprogress-wire C1 through a B1 make-contact 145 to this conductor 144.This Bl-interlock 145 constitutes the first resistance-reducingprogression-step of a service-application of dynamic brake, so that theconductor 144 is energized in joint response to a closure of thebrakingswitch B1, a full-field position of the field-controller FC, anda closure of the limit-relay back-contact 66 (Fig. 1B) in thebraking-progression circuit 71-74--73. As shown in Fig. 1C, theaforesaid conductor 144 is connected on, through a B2 back-contact 146,to a conductor 147, and thence to the B2 operating-coil, and to thepreviously mentioned circuit 137. A holding-circuit is immediatelycompleted from the hold-line C4 through a B2 make-contact'148 to theconductor 147.

Fig. 1C next shows a branch-circuit from the progressline C1 through aB3 back-contact 149 and a B2 makecontact 150 to a conductor 151, andthence through the B3 operating-coil to the previously mentioned circuit137. This circuit 137 is connected to the negative bus through twobranch circuits, one including the B4 back-contact 152 and the otherincluding a B5 make-contact 153. As soon as the B3 switch is actuated,it completes a holding-circuit from the hold-wire C4 through a B3make-contact 154 to the circuit 151.

In Fig. 1C, the bottom of the progress-wire C1 is shown as beingconnected through a circuit which extends through a. B5 back-contact 155to a conductor 156. A connection is made from the conductor 156' througha B3 make-contact 157 and a conductor 158 to the B4 energizing-coil, andthen to the negative bus As soon as the B4 switch picks up, it energizesa holding-circuit from the hold-wire C4 through a B4 make-contact 159 tothe aforesaid conductor 158.

The conductor 156, at the bottom of Fig. 1C, is also connected, througha branch-circuit which extends through a B2 back-contact 160, and a B4make-contact 161, to a circuit 162, and thence through the B5actuating-coil to the negative bus As soon as the B5 switch closes, itcloses a holding-circuit from the bottom of the hold-wire C4 in Fig. 1Cthrough a B5 make-contact 163 to the conductor 162.

The operation of the illustrated circuit-connections, which have nowbeen described, is shown in Fig. 2, which is a sequence chart which willsufiice as a basis for explaining the novel features of my invention.The general plan of the sequence chart is well known to all who arefamiliar with the past practices of the art, in controlling both thepower-operation and the dynamicbraking operation of traction-motors forelectrically propelled railway-cars. As is customary in this sort ofchart, a small circle indicates a closed position of a contact or anenergized condition of a coil or circuit. 1 shall direct my explanationmore particularly to the special features of my invention.

When the car is first being readied for operation, with reverser-drum RDof the master controller MC adjusted to either its forward or reverseposition, with the main drum MD of the master controller MC in itsoff-position, I and with no power on the supply-circuit 18 for themotors, as shown in step A of the sequence chart, the

supply-line 18 will first be energized, thereby picking up theline-relay LR as shown in step B. The doors of the train will then beclosed, closing all of the door-interlocks DI, and thus energizing thedoor-relay DR, as is indicated in step C of the chart.

The train is then ready for a power-operation, in which the brake-valveBV is moved to its oii-position, and the main drum of the mastercontroller MC is moved either immediately to its No. 3 on-position, orin a stcp-by-step manner to successive on-positions 1, 2 and 3,resulting in the well-known power-operation steps which are exemplifiedby steps P1 to P7, a transition step TR,

and steps P8 to P15 in Fig. 2.

When the motorman wishes to discontinue the poweroperation, he returnsthe controller through positions 2 and 1 to the off-position, resultingin steps PA, PB, C, D, E, F and 1 of the illustrative sequence chart,

which has been prepared on the assumption that the cutting off of powerfollowed a full-parallel, shuntedfield, operating-step P15, although itwill be understood,

of course, that the master controller could be returned to itsoff-position from any other step of the poweroperation of the motors.

As long as the master controller is in any oil-position, such as 2 or 1,as indicated by the steps PA and PB in the sequence chart, none of thepreviously closed motoroperating switches or contacts are disturbed,because they are all held by suitable holding-circuits which have beendescribed.

It will be noted that, when the controller is moved Y from its No. 1on-position, as shown in step PB, to its elf-position, the trainlinewire GS is first deenergized, as shown in step C of the chart, and thisdeenergizes the coil of the ground-switch G1. When the ground-switch G1opens, it deenergizes the main operating or closingcoils M and G of thetwo parallel-operation switches M and G through the G1 interlock 61, asshown in step D, causing these switches M and G to open. The opening ofthe switch G causes an opening of all of the resistance-switches R1 toR8, through the G interlock 100, as shown in step E of the chart. Theopening of the resistance-switch R2 causes an energization of thebraking-circuit switch B1, through the interlock 134, as shown in stepF, noting that the power-off switching-circuit 55 is now energized,through the G1 interlock 54.

Meanwhile, the master controller is continuing to move away from its No.1 on-position toward its oiI-position. At some time before theofi-position is fully reached, usually before the steps D and E of thesequence chart, but being shown, for convenience, as occurring after thestep E, the trainline wire 1 or 2- and the trainline wire 6 will both bedeenergized at the master controller, thereby deenergizing theline-switches LS1 and LS2, as shown in step F. When the line-switch LS1is open, its interlock 111 Will energize the two parallel-connectionswitches M and G, thereby completing a dynamic-braking circuit, in thespot-step 1, and also energizing the spot-coil SC, as shown in Fig. 2.During the continuance of the spotting condition of the dynamic-brakingcircuits, the limit-relay CR touches its back-contact 66 whenever thespotting-current is undesirably small, thereby notching thefield-controller FC toward its full-field position FF, through theprogression-circuit 717473C9. This operation is shown in steps '1, 2 and3 of the sequence chart.

If, now, the motorman desires a service application of dynamic braking,he moves the brake-valve BV to an on-position, moving it little or much,according to the amount'of braking which he desires. As shown in step 4of the sequence chart, this on-movement of the brakevalve BV resultsdirectly in actuating the brake-actuator BA from its deenergizedposition to an energized position. According to one feature of mypresent invention, the back-contact 27 of the brake-actuator BAthereupon opens and deenergizes the spot-coil SC, thus changing thecurrent-setting of the limit-relay CR from a small value suitable forspotting, to a large value suitable for producing a serviceable amountof a dynamic brake. At the same time, the brake-actuator BA opens itsbackcontact 69, thereby ensuring the deenergization of the shunt-fieldcoil FC-SF of the field-controller, even though the limit-relaymake-contact 67 might momentari- 1y close, thus preparing the way forthe progress-circuit 66--71--74-73--C9 to begin notching thefield-controller FC toward its full-field position FF, as shown in step4, and thereupon introducing the resistance-reducing part of thedynamic-braking progression, through the circuit 66717473-140C2-C23--C1,which is completed by the closure of the field-controller contact C23and the brake-actuator contact 140.

During the remainder of the dynamic-braking operation, successivesequence-steps are taken, in a well-known manner, as shown at steps 4 to15 of the sequence chart, each step being taken upon the subsidence ofthe braking-current to a value which is small enough to permit thelimit-relay CR to close its back-contact 66.

When the last two braking-steps 14 and 15 are taken, the dynamic-brakingoperation has substantially reached its fade-out point, the brakingeffort being very small, and the car-speed being close to zero, perhapssomething like three to five miles per hour. In step 15, the lastresistance-switch R8 is closed, and its interlock 28 deenergizes thelock-out magnet LOM, thus opening the lock-out valve LOV and bringingthe air-brake equipment into operation (or into stronger operation if ithad been in limited operation), so as to bring the car to a completestandstill.

It is a desirable feature of my invention that the dynamic-brakingcircuits, such as are shown in the last braking-step 15 of the sequencechart, shall be substantially interrupted (or completely interrupted asI have shown it), before the car comes to a complete stop. Heretofore,after the fade-out of a dynamic-braking operation, it has required theapplication of power to the tractien-motors A1 and A2, before theholding-circuits of the various switches in the dynamic-braking circuitcould be released; and this has sometimes resulted in a,

very undesirable situation in the event that one of the cars in amultiple-unit train had blown a third-rail fuse 17, unknown to theoperator at the head of the train, and if the operator had then made aservice dynamicbraking operation after this condition existed. Then,when a power-application was thereafter made, on the rest of the cars ofthe train, it would be impossible to make a power-application on thiscar with the burnt-out fuse, with the result that the dynamic-brakingcircuits of that car would remain energized, in an advanced state ofprogression, while that car is being towed by the rest of the train.This has resulted in a burning out of the resistances in thedynamic-braking circuit, because these resistances are not designed witha current-time rating sufiicient to withstand such sustained service.

In accordance with my invention, I provide a fadeout means whichinterrupts the dynamic-braking circuit in response to a reduction of thebraking-current to a preselectable value, such as 25 amperes or less, atwhich the dynamic-braking force becomes very small. This smallbraking-current value is preferably adjusted to be smaller than thatwhich closed the current-limit-relay back-contact 66 for the last time,so that this small current-value would be obtained during the periodwhile the air-brake equipment was bringing the car to a complete stop,after the lock-out magnet LOM had been released by the last brake-switchR8.

There are a number of specific circuits or control-means whereby thisfinal interruption of the dynamic-braking circuits could be obtained.Heretofore, at least since the introduction of the dynamic-brakingsystem of the Riley Patent 2,597,183, it has been customary to provide aspecial relay, which has been variously called a brakeprotective relay,or a brake-power relay, or other names, whereby to make sure that apower-operation has preceded a dynamic-brake operation, so as to makesure that there is enough residual magnetism remaining in the motors tosecure a reasonably sure and rapid buildup of the braking-currents whena dynamic-braking circuit is established. In systems using such abrake-protective relay, said relay could be controlled, in accordancewith my present invention, so as to deenergize this relay on fade-out,thus interrupting the dynamic-braking circuits and making it impossibleto reestablish such circuits until there has been anotherpower-operation of the traction-motors, as shown, for example, in mysimultaneously filed companion-application, Serial No. 675,489, filedJuly 31, 1957, now US. Patent No. 2,933,667, granted April 19, 1960,entitled Dynamic-Brake Control-Systems.

It is one of the features of my present invention to devise acircuit-means whereby I can avoid the use of as many extra relays aspossible. In my present invention, therefore, as shown in theaccompanying drawings, I use a special circuit-combination of interlockson the two power-circuit switches LS1 and G1, as a condition precedentto the establishment of a dynamic-braking circuit. Thus, I provide eachof my parallel-connection switches M and G with a hold-coil or circuit,which is not able to close the switch, but which is able to hold theswitch closed, once it has been closed. In the system which I haveshown, the establishment of a dynamic-braking circuit is brought aboutby an off-position of the two power-operation switches LS1 and G1.

If, however, a service-application of dynamic brake should be obtained,the energization of the parallel-combination switches M and G istransferred from battery power to braking-current power, during thedynamicbraking progression. In the specific illustrated circuit, whenthe braking-switch B5 closes, in the braking-Step8 of thesequence-chart, the B5 itnerlock 23 energizes the hold-coils M-Hold andG-Hold from the braking-circuitportiori 22T2, so as to supplement theaction of the main M and 'G coils which hold these switches closed bybattery-power; but whenthe fade-out point is substantially reached, asby the closure of the next-to-thelast resistance-switch R7, in step 14,the R7-interl0ck 121 opens and deenergizes the main coils M and G ofthese parallel-connection switches M and G for the brief remaining timein which the dynamic-braking circuit is in existence. Thebraking-current-energized hold-coils M-Hold and G-Hold keep theseswitches M and G energized, during the period when the car is beingbrought to a complete stop by the air-brake equipment, until the brakingcurrent has been reduced to a value which is smaller than that whichcaused a pickup of the R8 switch and set the air-brake equipment intooperation, in step 15 of the chart.

Thus, before the car comes to a complete stop, the braking-currentenergization of the M and G hold-coils M-Hold and G-Hold becomes toofeeble to keep these switches energized, and these switches thereuponopen their main contacts, thus interrupting the dynamic-braking circuitat M and G in the main-circuit diagram of Fig. 1A, as shown in thefade-out step of the sequence chart, Fig. 2.

The same general principal, of changing a suitable holding orenergizing-circuit of an electrically responsive switching-element, froman initial constant-voltage energization, such as is obtained from thebattery B, to a braking-current-responsive control, which finally dropsto a very small value, before the car comes to a complete stop, isgenerally applicable, within the broad concept of my invention, whetherit is applied to the parallel-connection switches M and G, or to aspecial brake-protective relay, or to any other means whereby this novelprinciple of operation may be embodied.

If, after fade-out, it is desired to again establish a power-operationof the motors, the motorman turns oil? the brake-valve BV and moves themaster controller to any on-position, such as the No. 1 position whichis shown in the transition-step TRl of the sequence chart. The firstmovement of the controller energizes the trainline wires 1 (or 2) and 6,as shown in the step TRl, but no switching changes are made in themotor-circuits, because of the open B1 interlock 46 in the energizingcircuit for the line-switch LS1. Immediately thereafter, the trainlinewire GS is energized, thus energizing the ground-switch G1, as shown instep TR2 of the chart. When the ground-switch G1 picks up, itdeenergizes all of the resistance-switches R1 to R8, and all of thebraking-switches B1 to B5, because of the opening of the G1 interlocks54 and 58, thus interrupting the braking-circuit connections, as shownin the step TR3 of the chart. The deenergization of the B1 switchenergizes the line-switch LS1, through the B1 interlock 46, resulting inthe circuitcondition shown in step TR4. The energization of theline-switch LS1 energizes the series-connection switch JR through theLS1 interlock 59, thus establishing a repetition of the firstpower-operation step P1, as shown on the chart.

Another desirable feature of my present invention is shown in the lastfive lines of the sequence chart, Fig. 2. It relates to a condition inwhich a door-interlock DI may have become open, or the continuity of thetrainline wire 21 may have otherwise become impaired, deenergizing thedoor-relay DR, unnoticed by the motorman, while the master-controller isin one of its on-positions. In previous equipments, using a brake-powerrelay (which I have now eliminated) to make sure that a power-operationhas preceded a dynamic-braking operation, and prior to the introductionof a so-called door-brake relay to correct the situation, as describedin my copending ap plication, Serial No. 642,742, filed February 27,1957, entitled Traction-Motor Control, an unnoticed interruption of thedoor-relay circuit has resulted in a deenergization of the brake-powerrelay, so that, when the motorman attempted to obtain dynamic braking,he could get no dynamic-braking circuits, resulting in a hazardoustrain-operating condition.

In my present invention, as shown in the last five lines of the sequencechart, I have assumed that the train is operating in one of thepower-operating steps, choosing the step P15 for illustrative purposes.1 have assumed, in the next step, marked with an asterisk that theopening of a door-interlock DI has resulted in a deenergizetion of thedoor-relay DR. The opening of the doorrelay contact 36, in Fig. 1A,deenergizes the train-line wires 1 (or 2) and GS, as shown in step andthis results in an opening of the two power-circuit switches LS1 and G1,as shown in the step The opening of the power-switches LS1 and G1results in the opening of the power-switch LS2, and all of theresistance-switches R1 to R8. This operation also results in theenergization of the full-field coil FC-FF of the field-controller FC,through the circuit 53--545558-'57-66-71--74 -73--C9. The result ismomentarily the condition shown in step *B, in which all of thepower-circuit switches are open.

As soon, however, as this occurs, the various interlocking circuits,which have been heretofore described, result in the establishment of aspotting circuit, as indicated by step *C in the sequence chart, whereinthe operating coils M and G of the parallel-connection switches M and Gare energized, the brake-switch B1 is energized, and the spot-coil SC isenergized, usually causing the limit-relay CR to pick up so as to closeits make-contact 67, thereby energizing the circuit 6869 7tl--C8C26-C7,which actuates the shunted-field coil FC-SF until the field-controllerPC is adjusted to its position F3 in Fig. 1. This results in theimmediate establishment of a spotting circuit-condition as shown in *Cin the last line of the sequence chart, Fig. 2, without waiting for themotorman to turn ofi the master controller, and making a servicebraking-application obtainable.

By way of conclusion, I will quickly summarize the principal novelfeatures of my present invention. I realize an appreciable saving in thecost of each equipment, in relays and wiring, and at the same time Iobtain several novel operational advantages.

I omit a formerly used brake-power relay, by adding a hold-coil orcircuit to the parallel-connection switches M and G (or other part ofthe spotting dynamic-braking circuit), and by rearranging theinterlocking controlcircuit connections so that a deenergized conditionof the two power-operation switches LS1 and G1 will set up thedynamic-braking circuit through an interlock (such as 121) on one of thelast two resistance-reducing switching-means which are actuated atsubstantially the fadeout point in the dynamic-braking progression. 1rearrange the holding-circuit, for holding this fade-out switching-meansin its energized position, through an out-interlock (such as 54) on oneof the power-operation switches, preferably the switch G1 which isresponsive directly to the trainline wire GS, so that a power-circuitoperation of the traction-motors is normally required, to open this G1interlock 54, before the dynamic-braking circuit can be againestablished after fade-out.

I avoid the necessity for a previously used brake-relay, by providinginterlocking contacts on the brake-actuator BA. The unobviousness ofthis seemingly simple expedient is shown by the history of thedevelopment and use of the brake-relay and the brake-actuator, Thebrakerelay was first introduced, as shown in my Patent 2,318,330, as ameans for causing a service brakingoperation to start simultaneously oneach of the cars in a multiple-unit train; and the brake-actuator wasused, at that time, to short out three successive taps on a resistor inseries with a rate-coil on the limit-relay, according to the amount ofair-pressure which was applied to the brake-actuator. Subsequently, asshown in Patent 2,523,143 of Riley and myself, a braking-responsiverheostat, similar to the rheostat BKG in my present application, wasused, which could be smoothly changed in.

asserted resistance, through many steps, and this rheos'tat was adjustedin position, dependent upon the amount of airpressure, preferably by theuse of the pressure-responsive brake-actuator. Subsequently, as shown inmy Patent 2,669,679, an over-shooting-preventing means was added to thebrake-actuator, to prevent this actuator from moving the adjustment-armon the braking-responsive rheostat too fast and too far, upon theinitial application of airpressure to the brake-actuator, but stillusing a special brake-relay for synchronizing the initiation or" aservice dynamic-braking operation in all of the cars of a multipleunittrain. This brief history will show how, little by little, the conceptsand uses of the braking relay and the brake-actuator have developed.

My present invention is based upon the known fact that the air-pressurein the straight-air pipe of any train varies so nearly simultaneously,in all of the cars of the train, that this air-pressure can be used tosubstantially simultaneously apply the air-brakes on all of the cars ofthe train, even in trains in which the braking power is obtained solelyby the air-brake equipment, without any dynamic braking. This being thecase, the initial re spouses of the brake-actuators on all of the carsof a multiple-unit train, regardless of the amount of braking which iscalled for by the air-pressure in the straight-air pipe, can be reliedupon to initiate the service dynamicbraking progression in all of thecars of the train, in times which are so nearly identical that theoperations can be regarded as being substantially simultaneous, for allpractical purposes.

My new control-circuit interlocking-arrangements also dispense with thenecessity for a door-brake relay, which Was more recently introduced forthe purpose of making possible a subsequent establishment of thedynamic-braking circuit, in the event that the power-operation of thetraction-motors is interrupted while the master-controller is'in anon-position. My use of the deenergized positions of the twopower-circuit switches LS1 and G1, to establish the dynamic-brakingcircuits, makes it possible for me now to omit such a door-brake relay.

My present control-circuits, by incorporating certain improvements, alsomakes it possible for me to avoid the use of a separate spotting-relay,for controlling the spotting-operations in the dynamic-braking circuits,prior to the initiation of a service braking-operation. I do this, byadding the spot-coil SC (or its equivalent) to the limit-relay CR, andby adding the limit-relay make-contact 67, and rearranging thecontrol-circuit connections. The history of the art shows that the useof a number of operating-coils on the limit-relay, including a spot-coilsuch as my coil SC, was known, with somewhat difierent control-circuitconnections, in my Patent 2,318,330, but it gave such a rough build-upof the dynamic-braking force, upon the initiation of a servicebraking-operation, that the spotting control had to be separated, again,from the limit-relay operations, as shown in Patent 2,523,143 of Rileyand myself.

Better control over the dynamic-braking build-up is now obtained, andovershoot, or rough braking-application are avoided, by adjusting therecalibrating resistance R15 in series with the kick-coil KC, onentering shunted-field operation, by means of the field-controllercircuits C5 and C6 and the field-controller contact-segment C25, and adistinction is made in the amount of recalibrating resistance R that isused, during dynamic braking as compared to the normalmotoring-operation, by means of the back-contact 30 on the secondline-switch LS2. This recalibration control is shown and claimed in myabovementioned copending application, Serial No. 642,742. Prior to that,other, less successful alternative means were devised, for preventingrough dynamic-braking build-up, as shown, for example, in Patent2,748,335, granted May 29, 1956, to Fowler and myself. We now use ourbrakeactuator contact 27 for taking our spot-coil SC out of operationwhen a service braking-operation is called for.

lit addition tosimplifying and reducing'the cost of my control-circuit,I have also achieved important functional oroperational advantages,particularly in connection with an open-circuiting of thedynamic-braking circuits before the car reaches zero speed during brakefade-out, a provision for the necessity for a reestablishment of apoweroperation before the dynamic-braking circuits can be againestablished after such a fade-out, and an immediate establishment of aspotting dynamic-braking circuit, without waiting for the mastercontroller to be returned to an olT-position, in response to the loss ofthe doorinterlock circuit, or a deenergization of the door-relay DR,during the operation of the car or train; all as has been hereinabovedescribed.

It will be understood that, in all such complicated control-circuitarrangements, such as are necessary for controlling the acceleration andthe dynamic-braking of an electrically propelled car, there are a greatmany alternative and substantially equivalent circuit-expedients, whichcan be used, and which from time to time are used, for accomplishingessentially the same results by essential equivalents of the samecircuit-means or expedients. While, therefore, I have illustrated myinvention in but a single exemplary arrangement, and while I havegreatly simplified this illustration by omitting many known teak tures,some of which would be practically necessary in any competitivelyacceptable control-system, I wish it to be clearly understood that I amnot altogether limited to the precise details of every illustratedconnection; and that the broader aspects of my invention contemplate thepossibility of the substitution of equivalents for one or more of thecircuit-elements, the addition of other circuit-elements which have notbeen shown in my simplified drawings, and the omission of details orelements which may not be needed in some installations.

I claim as my invention:

1. A control-assembly for two direct-current seriesmotor means for acommon load-device, each seriesmotor means including at least onemotor-armature, and a series field winding or windings; said assemblyincluding: a separate accelerating resistance for each of theseries-motor means; a motor-accelerating means, for energizing saidseries-motor means, first in a. series-motor connection and then in aparallel-motor connection, with said separate accelerating resistancesin series with their respective series-motor means, saidmotor-accelerating means including a motoring-progressionresistance-switching means for progressively reducing said acceleratingresistances in successive steps; a dynamic-braking means, forestablishing two dynamic-braking circuits wherein the armature orarmatures of each of said series-motor means are loaded by the fieldwinding or windings of the other series-motor means in series with oneof said acceleratingresistance means, said two dynamic-braking circuitshaving a common dynamic-braking circuit-portion, said twodynamic-braking circuits including an amount of braking resistance whichis not normally used in the motor-accelerating circuit, saiddynamic-braking means including a braking-progressionresistance-switching means for progressively reducing the amount of saidbraking resistance; a limit-relay means for delaying the aforesaidprogressions in response to excessive motor-current conditions; acontroller including an on-position means for actuating saidmotor-accelerating means, and an oil-position means for actuating saiddynamic-braking means; a braking-application control-means having anon-position and an offposition; a spotting-operation means, which isresponsive to the oil-position of the braking-application controlmeans,for interposing at least a partial block against the operation of saidbrakingprogression means when said braking-application control-means isin its non-actuated position; a braking-operation means, responsive tothe on-position of the braking-application control-rneans, for removingsaid block against the operation of said brak ing-progression means;other braking-means for bringing said series-motor means to a completestop; a first fadeout means, which is responsive to the dynamic-brakingcurrent when a fade-out condition is substantially reached in thedynamic-braking operation, for automatically bringing said otherbraking-means into operation; and a subsequently operating secondfade-out means, operative before said series-motor means comes to acomplete stop, for rendering said dynamic-braking circuit incapable ofagain producing a substantial dynamic-braking effect in case saidseries-motor means should again be driven at a substantial speed withoutfurther change in said dynamicbraking circuit; said limit-relay meansincluding a first current-responsive means which is responsive to themotor-current in a motor-accelerating portion of the motor-circuits, anda second current-responsive means which is selectively responsive to thedynamic-breaking current; said first current-responsive means beingdeterminatively effective in controlling the motor-accelerationprogressions and the braking-application progressions; and said secondcurrent-responsive means being determinatively efiective in controllingthe operation of said second fade-out means.

2. A control-assembly for two direct-current seriesmotor means for acommon load-device, each seriesmotor means including at least onemotor-armature, and a series field winding or windings; said assemblyincluding: a separate accelerating resistance for each of theseries-motor means; a motor-accelerating means, for energizing saidseries-motor means, first in a series-motor connection and then in aparallel-motor connection, with said separate accelerating resistancesin series with their respective series-motor means, saidmotor-accelerating means including a motoring-progressionresistance-switching means for progressively reducing said acceleratingresistances in successive steps; a dynamic-braking means, forestablishing two dynamic-braking circuits wherein the armature orarmatures of each of said series-motor means are loaded by the fieldwinding or windings of the other series-motor means in series with oneof said acceleratingresistance means, said two dynamic-braking circuitshaving a common dynamic-braking circuit-portion, said twodynamic-braking circuits including an amount of braking resistance whichis not normally used in the motor-accelerating circuit, saiddynamic-braking means including a banking-progressionresistanceswitching means for progressively reducing the amount of saidbraking resistance; a limit-relay means for delaying the aforesaidprogressions in response to excessive motor-current conditions; acontroller including an on-position means for actuating saidmotor-accelerating means, and an elf-position means for actuating saiddynamic-braking means; a braking-application control-means having anon-position and an offposition; a spotting-operation means, which isresponsive to the off-position of the braking-application controlmeans,for interposing at least a partial block against the operation of saidbraking-progression means when said braking-application control-means isin its non-actuated position; a braking-operation means, responsive tothe on-position of the braking-application control means, for removingsaid block against the operation of said brakingprogression means; otherbraking-means for bringing said series-motor means to a complete stop; afirst fade-out means, which is responsive to the dynamic-braking currentwhen a fade-out condition is substantially reached in the dyamic-brakingoperation, for automatically bringing said other braking-means intooperation; and a subsequently operating second fade-out means, operativebefore said series-motor means comes to a complete stop, forsubstantially open-circuiting said dynamic-braking circuit; saidlimit-relay means including a first currentresponsive means which isresponsive to the motor-current in a motor-accelerating portion of themotor-circuits, and a second current-responsive means which isselectively responsive to the dynamic-braking current; said firstcurrent-responsive means being determinatively cf- '22 fective incontrolling the motor-acceleration progressions and thebraking-application progressions; and said second current-responsivemeans being determinatively effective in controlling the operation ofsaid second fade-out means.

3. A control-assembly for two direct-current seriesmotor means for acommon load-device, each seriesmotor means including at least onemotor-armature, and a series field winding or windings; said assemblyincluding: a separate accelerating resistance for each of theseries-motor means; a power-switching circuit-means, for establishing apower-circuit for energizing said seriesmotor means, first in aseries-motor connection and then in a parallel-motor connection, withsaid separate accelerating resistances in series with their respectiveseries-motor means, said power-switching circuit-means including amotoring-progression resistance-switching means for progressivelyreducing said accelerating resistances in successive steps; abraking-switching circuit-means, for establishing two dynamic-brakingcircuits wherein the armature or armatures of each of said series-motormeans are loaded by the field winding or windings of the otherseries-motor means in series with one of said accelerating-resistancemeans, said two dynamic-braking circuits including an amount of brakingresistance which is not normally used in the motor-accelerating circuit,said two dynamic-braking circuits having an initial spotting brakingcondition in which very lttle braking-force is normally developed, saidbraking-switching circuit-means including braking-progressionresistanceswitching means for progressively reducing the amount of saidbraking resistance; a master controller including a plurality ofon-positions and an off-position; a means for ensuring that at least oneof the last of the braking-progression resistance-switching means, onceit is actuated, will be released only when the master-controller isthereafter moved to an on-position; a controlcircuit motoring-operationmeans, which is responsive to successive on-positions of the mastercontroller, for initiating, and controlling successive stages in, theoperation of said power-switching circuit-means; a control-circuitbraking-initiating means, which is jointly responsive to anoff-condition of said power-switch circuit-means, and to a releasedcondition of said one of the last of the braking-progressionresistance-switching means, for initiating the operation of saidbraking-switch circuit-means; a service-braking control-means which hasan on-position and an off-position; a dynamic-braking controlmeans,which is responsive to an on-position of said service-brakingcontrol-means, for converting said brakingswitching circuit means fromsaid spotting braking condition to a service braking condition in whicha substantial braking-force is normally developed under progressivelycontrollable dynamic-braking conditions; and a means, which is jointlyresponsive to an on-position of said service-braking control-means andto the absence of a substantial braking-current in said dynamicbrakingcircuits, for opening said dynamic-braking circuits.

4. A control-assembly for two direct-current seriesmotor means for acommon load-device, each seriesmotor means including at least onemotor-armature, and a series field winding or windings; said assemblyincluding: a supply-circuit for the motor-means; a poweravailabilityrelay, for indicating the existence of available power in apredetermined portion of said supply-circuit; a separate acceleratingresistance for each of the seriesmotor means; a power-switchingcircuit-means, for establishing a power-circuit for energizing saidseriesmotor means, first in a series-motor connection and then in aparallel-motor connection, with said separate accelerating resistancesin series with their respective seriesmotor means, said power-switchingcircuit-means including a motoring-progression resistance-switchingmeans assume 23 for progressively reducing said accelerating"resistancesin successive steps, said power-switching circuit-means including twoseparate power-circuit contactors, having serially connected contactswhich must both be closed in order to establish a motor-energizingcircuit; a brakings'witching circuit-means, for establishing twodynamicbraking circuits wherein the armature or armatures of each ofsaid series-motor means are loaded by the field winding or windings ofthe other series-motor means in series with one of saidaccelerating-resistance means, said two dynamic-braking circuitsincluding an amount of braking resistance which is not normally used inthe motor-accelerating circuit, said two dynamic-braking circuits havingan initial spotting braking condition in which very little braking-forceis normally developed, and a subsequent service braking condition inwhich a substantial brakingforce is normally developed, saidbraking-switching. circuit-means including braking-progressionresistance-switching means for progressively reducing the amount of saidbraking resistance; a master controller including a plurality ofon-positions and an off-position, said master controller having aplural-contact first on-position in which, when the master controller ismoved from the first on-position to the offposition, a first-openingcontact opens before a secondopening contact; a control-circuitmotoring-initiating means, which is responsive to the first on-positionof said master-controller, for initiating the operation of saidpower-switching circuit-means, under conditions wherein a first one ofsaid two power-circuit contactors is closed in joint response to saidsecondopening contact and said power-availability relay, and wherein thesecond one of said two-power-circuit contactors is closed in a moredirect response to said first-opening contact; a means for ensuring thatat least one of the last of the brakingprog'ression resistance-switchingmeans, once it is actuated, will be maintained in response to anon-actuated condition of said second power-circuit contactor;controlcircuit motoring-progression means, responsive to a more advancedon-position or positions of said master controller, for controllingsuccessive stages in the motoring progression; a control-circuitbraking-initiating means, which is jointly responsive to releasedconditions of both of said power-circuit contactors, and to a releasedcondition of said one of the last of the braking-progressionresistance-switching means, for initiating the operation of saidbraking-switch circuit-means; a service-braking control means which hasan on-position and an off-position; a dynamic-braking control-means,which is responsive to an on-position of said service-brakingcontrolmeans, for converting said braking-switching circuit means fromsaid spotting braking condition to a service braking condition in whicha substantial braking-force is normally developed under progressivelycontrollable dynamic-braking conditions; and a means, which is jointlyresponsive to an on-position of said servicebraking control-means and tothe absence of a substantial braking-current in said dynamic-brakingcircuits,

for opening said dynamic-braking circuits.

5. A control-assembly for an electrically propelled railway-car, whichis adapted to be operable either singly or as a unit of a multiple-unittrain; said control-assembly including: a motonmeans for propelling saidcar; a supply-circuit for the motor-means; a power-switchingcircuit-means, for establishing a power-circuit, for operating themotor-means under progressively controllable motoring conditions; abraking-switching circuit-means, for establishing a dynamic-brakingcircuit for the motormeans, in a spotting braking condition in whichvery little braking-force is normally developed; a master controllerincluding a plurality of on-positions and an offposition; acontrol-circuit means, which is responsive to successive on-positions ofthe master controller, for initiat-tug, and controlling successivestages in, the operation otfsaid' powenswite'hingi circuit means; acontrol-circuit means;- which is responsive to the off-position of themaster: controller, for initiating the operation of saidbraking-switching circuituneans; an air-brake assembly for bringing saidcar to a complete stop, said air-brake assembly comprising a pipe-line,a brake-valve for controllingthe air-pressurein' said pipe-line, abrake-actuator for responding to pressure in said pipe-line, an airbrake equipment for stopping said car, and an electrically controlledvalve for controlling the application of air-pressure from saidpipe-line to said air-brake equipment; a means, which is responsive toan operative condition of said braking-switch circuit-means, foractuating said electrically controlled valve; switch-interlock means,responsive to a-response of said brake-actuator, for converting saidbraking-switch circuit-means from said spotting braking condition to aservice braking condition in which a substantial braking-force isnormally developed under progressively controllable dynamic-brakingconditions; and a means, which is responsive to the absence of asubstantial braking-current in said dynamic-braking circuit, forreleasing said electrically controlled valve.

6. A control-assembly for an electrically propelled railway-car, whichis adapted to be operable either singly or as a unit of amultiple-unittrain; said control-assembly' including: a motor-means for propellingsaid car; a supply-circuit for the motor-means; a power-switchingcircuit-means, for establishing a power-circuit, for operating themotor-means under progressively controllable motoring conditions; abraking-switching circuitmeans, for establishing a dynamic-brakingcircuit for the motor means, in a spotting braking condition in whichvery little'braking-force is normally developed; a master controllerincluding a plurality of on-positions and an ottposition; acontrol-circuit means, which is responsive to successive on-positions ofthe master controller, for initiating, and controlling successive stagesin, the operation of said power-switching circuit means; acontrol-circuit means, which is responsive to the off-position of themaster controller, for initiating the operation of saidbraking-switching circuit-means; an air-brake assembly for bringing saidcar to a complete stop, said air-brake assembly comprising a pipe-line,a brake-valve for controlling the air-pressure in said pipe-line, abrake-actuator for responding to pressure in said pipe-line, anair-brake equipment for stopping said car, and an electricallycontrolled valve for controlling the application of air-pres sure fromsaid pipe-line to said air-brake equipment; a means, which is responsiveto an operative condition of said braking-switch circuit-means, foractuating said electrically controlled valve; switch-interlock means,responsive to a response of said brake-actuator, for converting saidbraking-switch circuit-means from said spotting braking condition to aservice braking condition in which a substantial braking-force isnormally developed under progressively controllable dynamic-brakingconditions; and a means, which is responsive to one of the last steps inthe service braking progression of the braking-switch circuit-means, forreleasing said electrically controlled valve.

7. A control system for a plurality of direct-current series motors,said system including line switch means for connecting said motors to adirect-current power source for operation of the motors, control meansfor controlling acceleration of the motors, motor switch means forestablishing a dynamic braking circuit for the motors, said brakingcircuit including a braking resistor, means for effecting progressiveshunting of the braking resistor in a predetermined sequence of steps,means for holding said motor switch means in closed position until theshunting of the braking resistor has reached ,a predetermined point insaid sequence, and means re- 8. A control system for a plurality ofdirect-current series motors, said system including line switch meansfor connecting said motors to a direct-current power source foroperation of the motors, control means for controlling acceleration ofthe motors, motor switch means for establishing a dynamic brakingcircuit for the motors, said braking circuit including a brakingresistor, means for effecting progressive shunting of the brakingresistor in a predetermined sequence of steps, means responsive tooperation of said line switch means to open position for efifectingoperation of said motor switch means to establish the braking circuit,current limit means energized upon establishment of the braking circuitfor etlecting control of the current in the braking circuit to limitsaid current to a low value, and brake actuator means for deenergizingsaid current limit means and for initiating said progressive shunting ofthe braking resistor.

9. A control system for a plurality of direct-current series motors,said system including motor switch means for connecting said motors inpower circuits for operation of the motors, line switch means forconnecting the motors to a direct-current power source and for effectingoperation of the motor switch means to establish said power circuits,control means nor controlling acceleration of the motors, brake switchmeans, means responsive to operation of the line switch means to openposition for effecting operation of the motor switch means and the brakeswitch means to establish a dynamic braking circuit for the motors, saidbraking circuit including a braking resistor, means for eiiectingprogressive shunting of the braking resistor in a predetermined sequenceof steps, current limit means energized upon establishment of thebraking circuit for effecting control of the current in the brakingcircuit to limit said current to a low value, brake actuator means fordeenergizing said current limit means and for initiating saidprogressive shunting of the braking resistor, means for holding saidmotor switch means in closed position during braking until the shuntingof the braking resistor has reached a predetermined point in saidsequence, and means responsive to the current in the braking circuit forthereafter holding the motor switch means closed until said currentfalls below a predetermined value.

10. A control system for a plurality of direct-current series motors,said system including series connection motor switches and parallelconnection motor switches for selectively connecting the motors in powercircuits, line switch means for connecting the motors to a directcurrent power source for operation of the motors, said motor switcheshaving operating means for efiecting operation of the motor switches toclosed position and for holding them closed as long as the operatingmeans are energized, control means for effecting operation of the lineswitches to closed position, the operating means of the motor switchesbeing energized in response to operation of the line switches to closedposition and under control of the control means to cause the motorswitches to operate in a predetermined sequence to establish said powercircuits, a brake switch, means responsive to operation of the lineswitches to open position for effecting energization of said parallelconnection switches and of said brake switch to establish a dynamicbraking circuit for the motors, means for controlling the current insaid braking circuit, means for effecting deenergization of theoperating means of the parallel connection motor switches, and holdingmeans for said motor switches energized in response to the current inthe braking circuit for holding the switches in closed position untilsaid current falls to a predetermined value.

ll. A control system for a plurality of direct-current series motors,said system including series connection motor switches and parallelconnection motor switches for selectively connecting the motors in powercircuits, line switch means for connecting the motors to a directcurrentpower source for operation of the motors, said motor switches havingoperating means for effecting operation of the motor switches to closedposition and for holding them closed as long as the operating means areenergized, control means for effecting operation of the line switches toclosed position, the operating means of the motor switches beingenergized in response to operation of the line switches to closedposition and under control of the control means to cause the motorswitches to operate in a predetermined sequence to establish said powercircuits, a brake switch, means responsive to oper ation of the lineswitches to open position for effecting energization of said parallelconnection switches and of said brake switch to establish a dynamicbraking circuit for the motors, said braking circuit including a brakingresistor, control means for effecting progressive shunting of thebraking resistor in a predetermined sequence of steps, means foreffecting deenergization of the operat ing means of the parallelconnection motor switches at a predetermined point in said sequence, andholding means for said motor switches energized in response to thecurrent in the braking circuit for holding the switches in closedposition until said current falls to a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS2,128,034 Austin Aug. 23, 1938 2,318,330 Purifoy May 4, 1943 2,523,143Riley Sept. 19, 1950 2,597,183 Riley May 20, 1952 2,637,008 Barclay Apr.28, 1953 2,669,679 Purifoy Feb, 16, 1954 2,693,562 Purifoy Nov. 2, 19542,712,103 Purifoy June 28, 1955 2,748,335 Purifoy May 29, 1956

